1. Field of the Invention
The present invention relates generally to circuits for measuring the time between two voltage transitions, and more particularly to a circuit for converting a time period to a dc voltage proportional to such period.
2. Description of the Prior Art
There are many requirements in the electronic art for obtaining quantitative measurements of time periods such as propagation delay, rise time, pulse widths, and periods of repetitive waveforms. A typical technique is described in U.S. Pat. No. 3,588,699 to Pysnik which measures the time between two signals utilizing voltage-controlled multivibrators. Janowitz et al in U.S. Pat. No. 3,999,128 teach the use of a comparator and sample and hold circuitry in driving a digital voltmeter. Other relevant U.S. patents are as follows: U.S. Pat. Nos. 3,461,392 to Hughes et al; 4,025,848 to Delagrange et al; 3,537,018 to Modiano; 4,246,497 to Lawsen et al; 3,940,693 to Brown; 3,787,765 to Morrow et al; and 3,805,153 to Gallant.